This invention relates to processing of heavy high-sulfur crude oils, and more particularly to processing of such crude oils which have properties making them difficult or impossible to process using conventional petroleum refining techniques.
It is generally accepted that the free world's available supply of high-gravity low-sulfur crude oil is becoming exhausted. Of necessity, less desirable crude oils, particularly high-sulfur crude oils, must be utilized to supply the products needed to provide energy for transportation, power and heating. Many existing refineries do not have the capability of processing high-sulfur crude oils.
Several processes have been suggested for handling low-gravity crude oils having a high sulfur content. Most of these processes include a desulfurization step and coking of at least a part of the material. However, in order to be usable, the coke product must have a relatively low sulfur content, such as from 0.5 to 1.5 percent by weight sulfur. Since some crude oils now being considered contain from four to as high as ten percent or more by weight sulfur, and since most products from such crude oils, in order to be environmentally and commercially acceptable, must contain much less sulfur than the crude oil feedstocks, it is apparent that a considerable amount of sulfur must be removed and disposed of when such high-sulfur crude oils are processed.
As an example, a single refinery processing 100,000 barrels per day of 9.5 weight percent sulfur crude oil would produce an amount of by-product sulfur equal to about five percent of the current domestic market. It is apparent that, in order for a significant amount of high-sulfur crude oil to be processed, some provision must be made for disposal of the huge quantities of by-product sulfur.
It has been proposed to utilize sulfur as a partial replacement for bitumen in asphalt road paving. This would provide an outlet for huge amounts of sulfur, such that processing of high-sulfur crude oil would not totally disrupt the sulfur market. A discussion of the sulfur paving process appears in the Aug. 11, 1976 issue of Chemical Week at page 20.